Choose the letter A, B, C or D to complete the sentences

When/ we/ go/ back/ the bookstore, we/ buy/ book/ we/ wanted.

• A. 
  When we go back to the bookstore, we will buy the book we wanted.
• B. 
  When we will go back to the bookstore, we buy the book we wanted.
• C. 
  When we go back to the bookstore, we buy the book we wanted.
• D. 
  When we will go back to the bookstore, we will buy the book we wanted.